In Text mode, the +CMGC command has the following syntax:
AT+CMGC=<fo>,<ct>[, <pid>[,<mn>[, <da>[,<toda>]]]]
After command line is terminated with <CR>, the module responds
sending a four-character sequence prompt:
<CR><LF><greater_than><space> (IRA 13, 10, 62, 32)
To send the message issue Ctrl-Z char (0x1A hex). To exit without
sending the message issue ESC char (0x1B hex).